A Snapback Solution for Ukraine

In their discussions about ending the war in Ukraine, Americans and Europeans are increasingly focused on providing Kyiv with security guarantees. After over a decade of conflict with Russia, including four years of all-out war, Ukraine understandably does not trust Moscow to abide by any cease-fire. Before Kyiv signs one, it wants assurances from its key partners that if Russia attacks again, Ukraine will not be left to fend for itself.

To meet this demand, some allies have suggested giving Ukraine assurances modeled on NATO's Article 5, which declares that an attack on one NATO country is an attack on all. Others have recommended stationing European troops in the country as a way to give such assurances teeth. But these proposals lack credibility. NATO allies have steadfastly refused to intervene directly in the current war, so any promise they make to fight Russia in a new one is simply not believable. The Kremlin knows this better than anyone, and such bluffs will not deter it.

American and European leaders can provide Ukraine with a real postwar guarantee. But to do so, they will have to stick to promises that are credible. And that means committing to a more intense version of their current behavior in the event that Russia violates a cease-fire deal. In other words, should Moscow attack Ukraine again, the country's allies would reimpose sanctions on Russia, provide new financial support to Kyiv, and offer Ukraine military assistance that goes beyond what they would offer in peacetime. The United States and its allies would codify these pledges into law and create mechanisms that activate them if Russia attacks.

These guarantees, of course, fall short of an Article 5-like pledge. But if combined with peacetime measures that strengthen the Ukrainian military (which will remain Kyiv's primary source of deterrence), they will still affect the Kremlin's calculus. The United States and Europe, then, can help ensure that any renewed aggression is prohibitively costly for Russia, even without directly intervening.